Method and apparatus for rehabilitating an underground water conduit and detecting and drilling a service entrance in the conduit

ABSTRACT

A method and apparatus for rehabilitating an underground water conduit having at least one service entrance including a plug having a light emitter which is responsive to the presence of an electromagnetic field, wherein the at least one service entrance is plugged with the plug and a semi-transparent membrane lining the internal surface of the underground water conduit thereby covering the plug. A drilling head is disposed on a body moveable within the underground water conduit, the drill head having a drill bit and a coil inductor concentric with the drill bit. The coil inductor is adapted to generate an electromagnetic field near the drilling head, wherein the light emitter of the plug is adapted to be turned on by the electromagnetic field emitted by the coil inductor to allow visual alignment of the drill bit with the light emitted by the light emitter through the semi-transparent membrane. The plug is drilled with the drill bit through the semi-transparent membrane in order to reopen the at least one service entrance.

TECHNICAL FIELD

The present invention relates to a method for rehabilitating anunderground water conduit and apparatus for detecting and drillingservice entrances in an underground water conduit that have beenpreviously plugged and covered by an internal lining during therehabilitation process of the underground conduit.

BACKGROUND

Underground water main conduits and/or sewage conduits that have beeninstalled decades ago have gradually deteriorated to the point wherepressurized treated water escapes through cracks and holes at rates thatcan reach 50%. Similarly. Sewage conduit may have become so deterioratedthat a substantial amount of sewage water seeps into the environmentinstead of being delivered to treatment facilities before re-enteringthe environment.

For many years now, technologies have been developed and used torehabilitate damaged water and sewage conduits. The various technologiesbasically consist of re-lining the inside walls of existing undergroundconduits to rehabilitate the underground conduits.

U.S. Pat. No. 5,497,807 describes a method of rehabilitating damagedconduits which consists of inserting a replacement pipe into theexisting conduit and filling the gap between the new and old pipe with afilling agent. However, this technology is limited to segments ofconduit that do not have side pipes or branch lines connected theretosince those would be blocked permanently. If used in conduits withmultiple service entrances or branch lines, each service entrance andbranch line would have to be individually reconnected to the mainconduit which would require digging the ground up to drill out therehabilitated conduit and reconnecting each branch line which isexpensive and time consuming.

U.S. Pat. No. 4,951,758 describes a method of rehabilitating damagedconduits which consists of initially plugging the service entrances ofthe existing conduit with a water plug carrying a position markeroscillating with a predetermined resonance frequency with a plug settingrobot controlled by a technician looking through a video cameraconnected to the plug setting robot and thereafter lining the existingconduit internally with a continuous strip of synthetic resin woundspirally and filling the gap between the new and old pipelines with afilling agent. Once the re-lining of the existing conduit is done, thewater plug can be located with a detection and drilling robot using aloop antenna connected to signal processing circuits which recognise thefrequency of the position marker and relay the intensity of the signalto the operator through a graphic display allowing the operator to zeroin on the center of the water plug by moving the robot past the waterplug until the signal diminishes in the horizontal direction andrepeating the process in the radial direction. Once the center of thewater plug is located, the water plug is drilled out using a drillmounted on the robot which is operated by the technician. Problems mayarise when there are multiple water plugs in the same area giving riseto multiple signals. To alleviate this problem, water plugs withposition marker having different resonance frequencies are used whenmultiple service entrances and branch lines in close proximity to eachother need to be plugged.

The method described in U.S. Pat. No. 4,951,758 works reasonably wellbut the detection process requiring multiple passes over the positionmarker of the water plugs in order to zero in on the center of the waterplugs is somewhat tedious and time consuming. As well, the use of waterplugs with position marker having different resonance frequenciesrequires a selection of water plugs to be carried inside the conduit bythe robot during the plug setting operation to prevent having to returnabove ground for water plugs with different resonance frequencies.

Therefore, there is a need for a method and apparatus for detecting anddrilling plugged service entrances in a conduit after rehabilitation ofthe conduit which would be less time consuming and eliminate some of thedrawbacks of prior art methods.

SUMMARY

Example embodiments of the present method and apparatus forrehabilitating a water or sewer conduit ameliorate at least some of theinconveniences present in the prior art.

Example embodiments of the present method and apparatus for detectingand drilling service entrances in a conduit after rehabilitation of theconduit increase the speed of the operation.

In one aspect, the invention provides a method for rehabilitating anunderground water conduit having at least one service entrance, themethod comprising the steps of: plugging the at least one serviceentrance with a plug having a light emitter which is responsive to thepresence of an electromagnetic field; lining the internal surface of theunderground water conduit with a semi-transparent membrane therebycovering the plug; with a drilling head having a drill bit and a coilinductor concentric with the drill bit, the coil inductor being adaptedto generate an electromagnetic field near the drilling head, generatingan electromagnetic field while moving the drilling head inside theunderground water conduit until the light emitter of the plug is turnedon by the electromagnetic field; visually aligning the drill bit withthe light emitted by the light emitter through the semi-transparentmembrane; and with the drill bit, drilling the plug in order to reopenthe at least one service entrance.

In another aspect, the invention further comprises a camera connected toa television monitor aboveground which is positioned in front of thedrilling head for visually detecting the light emitted by the lightemitter through the semi-transparent membrane and for aligning the drillbit with the light emitted by the light emitter.

In another aspect, the invention provides a service entrance plug to beused in the method for rehabilitating an underground water conduitcomprising at least one an antenna coil connected to the light emitter,the antenna coil being adapted to generate an electrical current whensubjected to an electromagnetic field that will turn on the lightemitter.

Embodiments of the present invention each have at least one of theabove-mentioned aspects, but do not necessarily have all of them.

Additional and/or alternative features, aspects, and advantages ofembodiments of the present invention will become apparent from thefollowing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a schematic cross-sectional view illustrating a deterioratedunderground water main conduit having three service entrances;

FIG. 2 is a schematic cross-sectional view of the deterioratedunderground water main conduit of FIG. 1 and a plug dispensing andsetting robot and camera assembly therein;

FIG. 3 is a schematic side elevational view of a service entrance plughaving a light emitting device in accordance with one embodiment;

FIG. 3 a is a schematic bottom plan view of the service entrance plughaving a light emitting device of FIG. 3;

FIG. 4 is a schematic side elevational view of a service entrance plughaving a light emitting device in accordance with a second embodiment;

FIG. 4 a is a schematic side exploded view of the service entrance plughaving a light emitting device of FIG. 4 a;

FIG. 5 schematic cross-sectional view of the deteriorated undergroundwater main conduit of FIG. 1 after a rehabilitation lining has beeninstalled therein;

FIG. 6 is a schematic cross-sectional view of the rehabilitatedunderground water main conduit of FIG. 5 and a plug detection anddrilling robot and camera assembly therein;

FIG. 7 is a schematic side elevational view of a drilling head of theplug detection and drilling apparatus in accordance with one embodiment;and

FIG. 8 is a schematic top plan view of the drilling head of FIG. 7.

DETAILED DESCRIPTION

FIG. 1 depicts a segment of an underground water main conduit 10 whichis in an advance state of deterioration. Water main conduit 10 includesmultiple holes, cracks or punctures 12 caused by excessive rust, cracksor soil movements, for example, that allow pressurized water to escapefrom the water main conduit 10 into the soil, generating drops inpressure and considerable waste of treated water. Water main conduit 10includes three service entrances 14, 16 and 18 linking water mainconduit 10 to households or businesses supplying fresh water to theoccupants.

When a segment of an underground water main conduit is in a state ofdeterioration as water main conduit 10 is depicted in FIG. 1, twooptions are available: Replacing the entire segment which entails thecostly and time consuming process of digging the ground up to remove thesegment of water main conduit 10 and install a new segment, or re-liningthe inside walls of the underground water main conduit 10 to cover andclose the multiple holes, cracks or punctures 12 and restore the insidewalls of the water main conduit 10 which is less expensive and timeconsuming.

The process of re-lining a segment of underground water main conduit 10requires that the service entrances 14, 16 and 18 be plugged prior tore-lining the water main conduit 10 to prevent any resin from seepinginto the service entrances and clogging them. As illustrated in FIG. 2,a plug setting robot 20 connected to a closed circuit camera 22 througha tension cable 24 at a predetermined distance are introduced togetherinto the water main conduit 10. The plug setting robot 20 and the camera22 are respectively connected to tension cables 27 and 29 which areconnected to a pair of winches (not shown) located above ground andoperated by a technician. The assembly of the plug setting robot 20 andcamera 22 is moved back and forth inside the water main conduit 10 byactuated one of the winches which pulls on one of the tension cables 27and 29 while the other winch offers little resistance. The assembly ofthe plug setting robot 20 and camera 22 is remotely operated by thetechnician looking at a television monitor (not shown) relaying liveimages captured by the camera 22.

The plug setting robot 20 comprises a main body 25 housing a power unitand actuator for controlling a dispensing head 30 positioned at thefront of the plug setting robot 20. The dispensing head 30 which isrotatable about an axis extending in a horizontal direction and movableback and forth in the horizontal direction for precise alignment withone of the service entrances 14, 16 or 18. The dispensing head 30 isalso movable in the radial direction to press a plug 32 into the serviceentrances. On top of the camera 22 is a magazine 28 housing a series ofplugs 32 aligned so that they may be retrieved one by one by thedispensing head 30. The plug setting robot 20 and the camera 22 aremounted on low friction pads 26 such that they can slide onto the bottomsurface of the inside wall of the water main conduit 10.

In operation, the technician, looking at a television monitor, moves theplug setting robot 20 to align the dispensing head 30 with one of theservice entrances 14, 16 or 18. The dispensing head 30 is then movedforward to retrieve a plug 32 or 33 from the magazine 28 located on topof the camera 22 and returned to its position in line with the serviceentrance 16 as illustrated FIG. 2. Minute adjustments are made in theradial direction by the technician viewing the alignment through hismonitor and then the plug 32 or 33 is inserted and pressed into theservice entrance 14 by the dispensing head 30 moving towards the serviceentrance 16. The dispensing head 30 is then retrieved and the technicianmoves the assembly of the plug setting robot 20 and camera 22 byactuating the winches to align the dispensing head 30 with anotherservice entrance and the cycle is repeated until all the serviceentrances 14, 16 or 18 are plugged.

As illustrated in FIG. 3, a first embodiment of the plug 32 includes ofa conical hollowed body 34 made of a soft plastic surrounded by a seriesof flexible winglets 36 adapted to bend when plug 32 is inserted intothe service entrance in order to efficiently seal the service entrance.The body 34 has first and second ends, wherein the smaller diameterfirst end is adapted to be inserted into a service entrance and thelarger diameter second end is adapted to be visually seen within theunderground water conduit. The bottom winglet 38, disposed on the secondend, has a larger diameter than the flexible winglets 36, is marginallythicker than flexible winglets 36 and is designed to rest on the edge orperimeter of the service entrance.

As illustrated in FIG. 3 a, the bottom winglet 38 includes an antennacoil 40 connected to a light emitter 42 located exactly in the center ofthe winglet 38. The antenna coil 40 is adapted to generate a smallelectrical current when subjected to an electromagnetic field that willturn on the light emitter 42.

With reference to FIGS. 4 and 4 a, a second embodiment of a plug isillustrated consisting of a two-piece plug 33 which also includes of aconical hollowed body 34 made of a soft plastic surrounded by a seriesof flexible winglets 36 adapted to bend when the hollowed body 34 isinserted into the service entrance in order to efficiently seal theservice entrance. The body 34 has first and second ends, wherein thesmaller diameter first end is adapted to be inserted into a serviceentrance and the larger diameter second end is adapted to be visuallyseen within the underground water conduit. The body 34 includes, in itssecond end, a receptacle winglet 37 having a larger diameter than theflexible winglets 36 designed to rest on the edge or perimeter of theservice entrance. The receptacle winglet 37 extends inwardly to definean annular lip 39 adapted to hold a cap 41 which is snapped into theannular lip 39 of the receptacle winglet 37 as shown in the explodedview of FIG. 4 a by the dotted arrow. The snap-on cap 41 includes agroove 43 which secures the snap-on cap 41 to the annular lip 39 of thereceptacle winglet 37. The antenna coil 40 and light emitter 42 shown inFIG. 3 a are embedded in the snap-on cap 41.

In operation, the installation of the two-piece plug 33 into the serviceentrances 14, 16 and 18 may be a one step process in which the assembledtwo-piece plug 33 including the cap 41 is inserted and pressed into theservice entrances by the plug setting robot 20 as previously described,or a two step process in which the body 34 of the two-piece plug 33 isfirst inserted and pressed into a service entrance by the plug settingrobot 20 and then the plug setting robot 20 retrieves a cap 41 includingthe light emitter 42 from a second a magazine (not shown) housing aseries of caps 41 which it inserts into the internal groove 39 of thereceptacle winglet 37 of the body 34 previously inserted and pressedinto the service entrance.

Once all the service entrances 14, 16 and 18 are plugged with the plugs32 or 33 comprising a light emitter 42, the segment of underground watermain conduit 10 may be re-lined. A tubular membrane 50 comprising of apair of concentric circular weave polyester fiber hoses impregnated withepoxy resin is introduced inside the water main conduit 10. The tubularmembrane is cooked with hot water under pressure such that the tubularmembrane 50 adheres to the inner wall of the water main conduit 10. Inthe cooking operation, the resin migrates into the circular weavepolyester fibre hoses and renders the tubular membrane 50 semitransparent when the resin has cured. As illustrated in FIG. 5, when thetubular membrane 50 has cured and solidified, the multiple holes, cracksor punctures 12 of water main conduit 10 described with reference toFIG. 1 are completely covered and the water main conduit 10 iswatertight. In the process, the service entrances 14, 16 and 18 are alsocompletely covered by the tubular membrane 50.

Once the tubular membrane 50 has cured and solidified, the serviceentrances 14, 16 and 18 must be located and the plugs 32 or 33 drilledout in order to re-open the service entrances 14, 16 and 18 to supplywater to the residences or businesses linked to the water main conduit10 through the service entrances 14, 16 and 18.

To locate the plugs 32 or 33 and drill them out, a drilling robot 60connected to a closed circuit camera 22 and a generator 61 areintroduced together into the tubular membrane 50 of the water mainconduit 10 as illustrated in FIG. 6. The drilling robot 60, the camera22 and the generator 61 are connected together as an assembly throughtension cables 24. The drilling robot 60 and the generator 61 arerespectively connected to tension cables 27 and 29 which are connectedto a pair of winches (not shown) located above ground and operated by atechnician. The assembly of the drilling robot 60, the camera 22 and thegenerator 61 is moved back and forth inside the water main conduit 10 byactuated one of the winches which pulls on one of the tension cables 27and 29 while the other winch offers little resistance. The drillingrobot 60 and the generator 61 are mounted on low friction pads 64 suchthat they can slide on the inside of the tubular membrane 50 within thewater main conduit 10. The assembly is remotely operated by thetechnician looking at a television monitor (not shown) relaying liveimages captured by the camera 22.

The drilling robot 60 comprises a main body 62 housing a power unit andactuator for controlling a drilling head 66 positioned at the front ofthe drilling robot 60. The drilling head 66 includes a drill bit 68extending perpendicular to main body 62 and the longitudinal axis of thewater main conduit 10. The drilling head 66 is rotatable about an axisextending in a horizontal direction and also movable back and forthalong the same axis such that the technician is able to precisely alignthe drill bit 68 with service entrances located in any position aroundthe circumference of the water main conduit 10.

With reference to FIGS. 7 and 8 which are enlarged views of the drillinghead 66, a coil inductor 70 is mounted on the drilling head 66. Thewinding of the coil inductor 70 is concentric with the axis of the drillbit 68 and preferably oval shaped as illustrated in FIG. 8 in order toprovide a wider sweep than a regular round shape. Referring back to FIG.6, the generator 61 is electrically connected directly to the coilinductor 70 through an electrical wire 72 to provide the requiredelectrical current to the coil inductor 70. When an electrical currentflows through the coil inductor 70, the coil inductor 70 generates anelectromagnetic field.

With reference to FIG. 6, in operation, the drilling robot 60 is movedinside the water main conduit 10 by the technician into an area whereone of the service entrances 14, 16, or 18 was plugged by a plug 32 or33. The technician then activates the coil inductor 70 to generate anelectromagnetic field. When the electromagnetic field generated by thecoil inductor 70 is in the vicinity of a plug 32 or 33, the antenna coil40 of the plug 32 or 33 generates a small electrical current that turnon the light emitter 42. The semi transparent characteristic of thetubular membrane 50 allows the light emitted by the light emitter 42 topass through the tubular membrane 50 such that the light can be seen bythe technician through the camera 22 positioned directly in front of thedrilling head 66. The light emitted is preferably red and flashing forease of detection.

The technician is able, through the camera 22, to visually align the endof the drill bit 68 with the flashing red light by moving the drillingrobot 60 back and forth, by rotating the drilling head 66, and movingthe drilling head 66 up and down to be as close as possible to thesurface of the tubular membrane 50 and to the flashing red light suchthat the end of the drill bit 68 is precisely aligned with the plug 32located behind the tubular membrane 50. Since the light emitter 42 isexactly in the center of the plug 32 or 33 as previously described, thealignment of the end of the drill bit 68 with the flashing red lightaligns the drill bit 68 with the center of the plug 32 or 33 andtherefore the center of the service entrance 14. Once the alignment isdone, the technician actuates the drill bit 68 and proceeds withdrilling out the plug 32 or 33 by moving the drilling head 66 throughthe tubular membrane 50 and through the plug 32 or 33 located behind thetubular membrane 50 far enough to completely drill out the plug 32 or33. The drilling head 66 is then retrieved and the drilling robot 60 ismoved into an area where another of the service entrances 14, 16, or 18was plugged by a plug 32 or 33 and the cycle of detection, alignment anddrilling is repeated until all the plugs 32 or 33 have been drilled outand all the service entrances 14, 16 and 18 reopened.

The combination of the light emitter 42 positioned at the center of theplug 32 or 33 responsive to the electromagnetic field generated by thecoil inductor 70 enables the technician to visually align the drill bit68 with the center of the plug 32 or 33 as opposed to relying on someother signals which has the beneficial effect of accelerating thedrilling process and therefore accelerating the reopening of the watermain conduit 10 after rehabilitation.

Modifications and improvements to the above-described embodiments maybecome apparent to those skilled in the art. The foregoing descriptionis intended to be exemplary rather than limiting. The scope of thepresent invention is therefore intended to be limited solely by thescope of the appended claims.

What is claimed is:
 1. A method for rehabilitating an underground waterconduit having at least one service entrance, the method comprising:plugging the at least one service entrance with a plug having a lightemitter which is responsive to the presence of an electromagnetic field;lining the internal surface of the underground water conduit with asemi-transparent membrane thereby covering the plug; generating anelectromagnetic field with a coil inductor disposed on a drilling headhaving a drill bit, wherein the coil inductor is adapted to generate anelectromagnetic field near the drilling head; moving the drilling headinside the underground water conduit until the light emitter of the plugis turned on by the electromagnetic field emitted by the coil inductor;aligning the drill bit with the light emitted by the light emitterthrough the semi-transparent membrane; and drilling the plug with thedrill bit through the semi-transparent membrane in order to reopen theat least one service entrance.
 2. The method of claim 1, wherein thestep of aligning the drill bit utilizes a camera connected to atelevision monitor aboveground and positioned in front of the drillinghead for visually detecting the light emitted by the light emitterthrough the semi-transparent membrane and for aligning the drill bitwith the light emitted by the light emitter.
 3. The method of claim 2,wherein the step of drilling includes remotely operating the drillinghead by a technician aboveground looking at the television monitorrelaying live images captured by the camera.
 4. The method of claim 3,wherein the step of drilling further includes moving the drilling headrotatably and back and forth along a horizontal axis of the undergroundwater conduit.
 5. The method of claim 1, wherein the light emitter islocated in the center of the plug.
 6. The method of claim 1, wherein thecoil inductor is wound in an oval shape.
 7. A system for rehabilitatingan underground water conduit having at least one service entrance, thesystem comprising: a plug having a light emitter which is responsive tothe presence of an electromagnetic field, wherein the at least oneservice entrance is plugged with the plug; a semi-transparent membranelining the internal surface of the underground water conduit therebycovering the plug; a drilling head disposed on a body moveable withinthe underground water conduit, the drill head having a drill bit and acoil inductor concentric with the drill bit, the coil inductor beingadapted to generate an electromagnetic field near the drilling head,wherein the light emitter of the plug is adapted to be turned on by theelectromagnetic field emitted by the coil inductor to allow visualalignment of the drill bit with the light emitted by the light emitterthrough the semi-transparent membrane.
 8. The system of claim 7, furthercomprising a camera connected to a television monitor aboveground andpositioned in front of the drilling head for visually detecting thelight emitted by the light emitter through the semi-transparent membraneand for aligning the drill bit with the light emitted by the lightemitter.
 9. The system of claim 8, wherein the drilling head is remotelyoperable by a technician aboveground looking at the television monitorrelaying live images captured by the camera.
 10. The system of claim 9,wherein the drilling head is rotatable about an axis extending in ahorizontal direction of the underground water conduit and movable backand forth along the horizontal axis.
 11. The system of claim 7, whereinthe light emitter is located in the center of the plug.
 12. The systemof claim 7, wherein the coil inductor is wound in an oval shape.